/*
 * Copyright 2011-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.sabayframework.channel.impl;

import org.sabayframework.channel.Channel;
import org.sabayframework.channel.Lock;

/**
 * A base class for a channel implementation.
 * @author Alex Antonau
 * */
public abstract class AbstractChannel<T> implements Channel<T> {

    /** Throwable that caused an error during queue processing */
    private volatile Throwable failure;

	@Override
	public void fail(Throwable cause) {
		this.failure = cause;
		close();
	}

	@Override
	public boolean hasFailed() {
		return failure!=null;
	}

	@Override
	public Throwable getFailureCause() {
		return failure;
	}
	
	@Override
	public void add(T elem) throws IllegalStateException {
		final Lock<T> lock = getWriteLock(1);
		if(lock!=null){
			try{
				lock.set(0, elem);
			}finally{
				lock.unlock();
			}
		}else throw new IllegalStateException();
	}
	
	@Override
	public T remove() throws IllegalStateException {
		final Lock<T> lock = getReadLock(1);
		if(lock!=null){
			try{
				return lock.get(0);
			}finally{
				lock.unlock();
			}
		}else throw new IllegalStateException();
	}
	
	@Override
	public String toString() {
		StringBuilder sb=new StringBuilder();
		sb.append(super.toString());
		sb.append("[size=").append(size());
		sb.append(", closed=").append(isClosed()).append("]");
		return sb.toString();
	}


}
